Obesity occurs when energy intake exceeds energy expenditure. Humans expend energy through purposeful exercise and through changes in posture and movement that are associated with the routines of daily life [called nonexercise activity thermogenesis (NEAT)]. To examine NEAT's role in obesity, we recruited 10 lean and 10 mildly obese sedentary volunteers and measured their body postures and movements every half-second for 10 days. Obese individuals were seated, on average, 2 hours longer per day than lean individuals. Posture allocation did not change when the obese individuals lost weight or when lean individuals gained weight, suggesting that it is biologically determined. If obese individuals adopted the NEAT-enhanced behaviors of their lean counterparts, they might expend an additional 350 calories (kcal) per day.

Energy expenditure more than doubles when sedentary screen time is converted to active screen time. Such interventions might be considered for obesity prevention and treatment.

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Objectives-Children and adults spend large portions of their days in front of screens. Our hypothesis was that both children and adults would expend more calories and move more while playing activity-promoting video games compared to sedentary video games.Study Design-In this single-group study, twenty-two healthy children (12 ± 2 years, 11 M, 11 F) and 20 adults (34 ± 11 years, 10 M, 10 F) were recruited. Energy expenditure and physical activity were measured while participants were resting, standing, watching television seated, sitting and playing a traditional sedentary video game, and while playing an activity-promoting video game (Nintendo® Wii™ Boxing). Physical activity was measured using accelerometers and energy expenditure was measured using an indirect calorimeter.Results-Energy expenditure increased significantly above all activities when children or adults played Nintendo® Wii™ (mean increase over resting, 189 ± 63 kcal/hr, p < 0.001, and 148 ± 71 kcal/hr, p < 0.001, respectively). Upon examination of movement using accelerometry, children moved significantly more than adults (55 ± 5 AAU and 23 ± 2 AAU, respectively, p < 0.001) while playing Nintendo® Wii™.Conclusions-Activity-promoting video games have the potential to increase movement and energy expenditure in children and adults.

The pilot, unsupervised walking intervention increased the MPA of overweight and obese women during pregnancy.

The mediator of the interaction between positive energy balance and physical activity is unknown. In this study, we address the hypothesis that orexin A acts in the hypothalamic paraventricular nucleus (PVN) to increase nonfeeding-associated physical activity. PVN-cannulated rats were injected with either orexin A or vehicle during the light and dark cycle. Spontaneous physical activity (SPA) was measured using arrays of infrared activity sensors and night vision videotaped recording (VTR). O2 consumption and CO2 production were measured by indirect calorimetry. Feeding behavior was assessed by VTR. Regardless of the time point of injection, orexin A (1 nmol) was associated with dramatic increases in SPA for 2 h after injection (orexin A: 6.27 Ϯ 1.95 ϫ 10 3 beam break count, n ϭ 24; vehicle: 1.85 Ϯ 1.13 ϫ 10 3 , n ϭ 38). This increase in SPA was accompanied by compatible increase in O2 consumption. Duration of feeding was increased only when orexin A was injected in the early light phase and accounted for only 3.5 Ϯ 2.5% of the increased physical activity. In a dose-response experiment, increases in SPA were correlated with dose of orexin A linearly up to 2 nmol. PVN injections of orexin receptor antagonist SB-334867 were associated with decreases in SPA and attenuated the effects of PVN-injected orexin A. Thus orexin A can act in PVN to increase nonfeeding-associated physical activity, suggesting that this neuropeptide might be a mediator of NEAT. energy expenditure; hypothalamus; obesity; nonexercise activity thermogenesis OBESITY AFFECTS ONE-THIRD of the American population and is the second leading cause of death in the United States after smoking (1). Treatment of obesity has proven difficult, and this intractability may be due to the fact that energy balance is regulated through multiple and complex mechanisms that are not fully understood (4). Maintenance of body weight is achieved by an intricate balance between energy intake and expenditure. We found that changes in nonexercise activity thermogenesis (NEAT) mediate resistance to weight gain with overfeeding in sedentary adults (32). There is evidence that "spontaneous" physical activity (SPA) is familial (63) and shows marked interindividual differences in its contribution to daily energy expenditure (49); however, the mediator of the interaction between overfeeding and physical activity is unknown.Orexins (A and B, also known as hypocretin 1 and 2) are recently identified neuropeptides synthesized exclusively in the lateral hypothalamus, an area classically believed to be a crucial "feeding" center (25). Initial interest in these neuropeptides concentrated on their orexigenic actions, since central injection of orexins increased food intake, and prepro-orexin mRNA was shown to be upregulated with fasting (50). Apart from appetite regulation, orexins have been implicated in the central nervous system (CNS) regulation of arousal and sleep, cardiovascular function, temperature, metabolic rate, locomotor activity, pituitary secretion, glucose homeostasis, ...

OBJECTIVE-Diminished daily physical activity explains, in part, why obesity and diabetes have become worldwide epidemics. In particular, chair use has replaced ambulation, so that obese individuals tend to sit for ϳ2.5 h/day more than lean counterparts. Here, we address the hypotheses that free-living daily walking distance is decreased in obesity compared with lean subjects and that experimental weight gain precipitates decreased daily walking.RESEARCH DESIGN AND METHODS-During weight-maintenance feeding, we measured free-living walking using a validated system that captures locomotion and body movement for 10 days in 22 healthy lean and obese sedentary individuals. These measurements were then repeated after the lean and obese subjects were overfed by 1,000 kcal/day for 8 weeks.RESULTS-We found that free-living walking comprises many (ϳ47) short-duration (Ͻ15 min), low-velocity (ϳ1 mph) walking bouts. Lean subjects walked 3.5 miles/day more than obese subjects (n ϭ 10, 10.3 Ϯ 2.5 vs. n ϭ 12, 6.7 Ϯ 1.8 miles/day; P ϭ 0.0009). With overfeeding, walking distance decreased by 1.5 miles/day compared with baseline values (Ϫ1.5 Ϯ 1.7 miles/day; P ϭ 0.0005). The decrease in walking that accompanied overfeeding occurred to a similar degree in the lean (Ϫ1.4 Ϯ 1.9 miles/day; P ϭ 0.04) and obese (Ϫ1.6 Ϯ 1.7 miles/day; P ϭ 0.008) subjects.CONCLUSIONS-Walking is decreased in obesity and declines with weight gain. This may represent a continuum whereby progressive increases in weight are associated with progressive decreases in walking distance. By identifying walking as pivotal in weight gain and obesity, we hope to add credence to an argument for an ambulatory future. Diabetes 57:548-554, 2008 O besity is epidemic in developed countries and is emerging in middle-and even low-income countries; this in part explains the unprecedented increase in type 2 diabetes worldwide (1). It is widely agreed that this partially reflects mounting sedentariness (2,3). At the beginning of the 20th century 90% of the population of the world was rural. However, over the last century, more than two billion agriculturalists have become city dwellers (4). In the latter transition, physical activity has declined (5). In particular, chair use has replaced ambulation (6) such that obese individuals tend to sit for ϳ2.5 h/day more than lean counterparts (7). Walking is the principal component of nonexercise activity thermogenesis (NEAT), which is the energy expenditure association with free-living daily activities (8,9). This is because people walk for several hours each day and, even at slow velocity, walking doubles energy expenditure (10); hence, the product of the time engaged in walking and its energetic equivalent is numerically substantial. We therefore wondered whether walking might be mechanistically important in weight gain and obesity. To address the hypothesis that free-living daily walking distance is decreased in obesity, we examined the characteristics of free-living walking in lean and obese people. Then, to address the hypothesis t...

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